Robert Nuster

Dr. Robert Nuster, Institute of Physics, University of Graz, Austria

Dr Robert Nuster is a senior researcher at the Institute of Physics at the University of Graz, Austria. He received his PhD in Physics from the University of Graz and has extensive expertise in photoacoustic imaging and laser ultrasound. His research focuses on optical ultrasound generation and detection, structured light/sound generation and application, metamaterials, multimodal imaging, image reconstruction, and laser-ultrasound-based materials characterization. His work combines fundamental research with technological development for applications ranging from biomedical imaging to industrial applications in the field of process monitoring and material inspection.

Photoacoustics and Laser Ultrasound at the University of Graz: From Novel Technologies to Biomedical and Industrial Applications

Photoacoustics and laser ultrasound are highly interdisciplinary fields at the interface of optics, acoustics, thermodynamics, materials science, and biomedical research. Beyond fundamental wave propagation and interaction phenomena, advances in ultrasound generation and detection, signal processing, and image reconstruction enable applications from biomedical imaging to industrial materials characterization.

This talk provides an overview of current and future research activities at the University of Graz. In photoacoustic imaging, we develop camera-based optical ultrasound detection [1-2] and explore various structured light concepts for coded excitation to enhance image quality and imaging speed [3]. In addition, we investigate directional optical ultrasound detection concepts utilizing the properties of structured light for acoustic source localization [4], as well as multifunctional imaging technologies based on optical and acoustic metamaterials [5].

In laser ultrasound, our research spans a wide range of length scales, from the sub-micrometer to meters.Applications include residual stress analysis and the characterization of nonlinear acoustic parameters in mechanically loaded metals [6], online process monitoring in industrial steel casting, quality control of laser welding processes [7-9], and semiconductor characterization and defect detection [10-11].

A further focus is multimodal imaging that combines photoacoustic, optical, and ultrasound methods using broadband optical ultrasound generation and detection [12-13]. Future research will target the miniaturization and integration of these technologies using photonic integrated circuits (PICs), paving the way for compact, high-performance sensing and imaging systems for biomedical and industrial applications.

References:
[1] K. Schitter, G. Paltauf, and R. Nuster, "Light-sheet photoacoustic imaging with camera-based ultrasound detection," in European Conferences on Biomedical Optics 2025, Technical Digest Series (Optica Publishing Group, 2025), paper W4C.1. https://doi.org/10.1364/ECBO.2025.W4C.1

[2] R. Nuster, P. Slezak, and G. Paltauf, "High resolution three-dimensional photoacoustic tomography with CCD-camera based ultrasound detection," Biomed. Opt. Express 5, 2635-2647 (2014), https://doi.org/10.1364/BOE.5.002635

[3] P. R. Torke, R. Nuster, and G. Paltauf, "Photoacoustic computational ghost imaging," Opt. Lett. 47, 1462-1465 (2022). https://doi.org/10.1364/OL.452229

[4] M. Main, R. Nuster, P. Banzer, M.P.J. Lavery, Acoustic pressure wave orientation determination using structured light, Opt. Express 34 (2026) 6217–6228. https://doi.org/10.1364/OE.580614.

[5] D.S.H. Brandmüller, D. Grafinger, R. Nuster, A. Hohenau, M. Ossiander, P. Banzer, Photoacoustic microscopy with meta-optics, Commun Phys 8 (2025). https://doi.org/10.1038/s42005-025-02350-4.

[6] M. Saurer, M. Ruetz, F. Diemling, P. Bauer, L.-M. Froehlich, A. Deisl, H.-P. Gaenser, T. Antretter, R. Nuster, G. Paltauf, “Temperature-Dependent Stress Monitoring in Solids Using Laser Ultrasound”, Journal of Applied Physics, submitted 2026, Status: under review

[7] M. Saurer, G. Paltauf, O. Spitzer, T. Reitmayer, G. Djuras, B. Kornberger, U. Kleb, R. Nuster, „Artificial intelligence-assisted laser ultrasound method for the estimation of porosity in hairpin weld seams,” Photoacoustics, Volume 46, 2025, 100770, ISSN 2213-5979, https://doi.org/10.1016/j.pacs.2025.100770